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Wow. "Make your own vacuum tube" Answered

This is pretty amazing:

Video on making a vacuum tube by hand.

(Lets see if Instructables likes Dailymotion videos...)


It's a STEAMPUNK transistor! A heated filament (cathode) emits electrons that travel through vacuum to the anode. By putting assorted "grid" electrodes in between at various voltage, the amount of current that flows can be controlled. Naturally, the voltages involved are quite high, and the current used just to heat the filament is substantial. Aside from that, a vacuum tube behaves pretty-much like a field-effect transistor. The last surviving member of the vacuum tube family in common use is the CRT Tv-screen, where the anode is covered with phosphor, and some of the additional control signals managed to make the electrons travel in a tiny beam that is swept across the screen in a raster pattern to make pictures.

They are pretty inefficient.. but they can carry higher amperage... right?

Some of the remaining applications for vacuum-tube like devices involve very high current, voltage, and power (eg, the magnetron that produces the microwaves in your oven is a kind of vacuum tube), but I don't think that it's fair to say that a generic vacuum tube is a higher amperage device than a generic solid state device. One of the factors that comes into play that it is relative easy to scale UP a vacuum tube compared to a semiconductor junctions (which is sort of inherently a nanoscale device.)

Am I getting this right?:
besides the heater element , there are 3 other components: grid, cathode and anode
the grid = input , low voltage
anode and cathode are on a high voltage powersupply(around 200-400v) , the speaker sits between the anode(or cathode?) and the tube , but since it works with such a high voltage , a transformer must be placed between the output of the tuba and the speaker, so a lower voltage reaches the speaker...
something like that?
Just started getting interested in vacuum tubes and i'm trying to make a simple 5 watt amplifier , but i need to know how they work first...

Yes, that's about right. You have all the complications of more modern circuits as well; high power amplifiers tend to be "push/pull" configurations, for example.

First of all, vacuum tubes were the predesessors to the transisters and were in common use until the late 1960's. I can remember, as a child, observing the glow of vacuum tubes in the back of my dad's stereo. Until the invention of the field effect transistors(FET), the vacuum tube was the only high input impedience(resistance) amplifier. Vacuum tubes were also capable of handling high currents which would have fried the early transistors. As a side note, the first electronic digital computer was built from vacuum tubes, filled an entire room and weighed several tons! Thank goodness for integrated circuits! For the most part, vacuum tubes faded from sight. Gone are the drug store tube testers. However, they are still used in some high-end audio synthesizers and amplifiers. Most of your large (not practice-sized) guitar amplifiers use vacuum tubes. Vacuum tube synthesizers are prized by digital composers add a degree of warmth and pleasant distortion to the sound.

Speaking of Vacuum tube computers, in 1951, Popular Science magazine said that someday, computers may actually weigh less than 1.5 tons (at the time it was ridiculed).

I'd rather buy one...

Wow...Hardcore DIY there... That would be interesting to see in kit form. You could have different levels: raw materials, formed materials, subassemblies, etc.

I suspect that the last part; sealing the tube while you have it full of vacuum, is one of the hardest to do...

True, a lot of this is fairly advanced stuff. Then again, building an airplane is tricky, and there's kitplanes everywhere. A lot of the professional equipment could probably be substituted with blowtorches, etc., but the vacuum sealing could be a mail-in deal. Then again, I know very little about glassblowing, so maybe I should just shut up right now before I embarrass myself.

I suppose it could be done via a permanent valve... like have a sealed on valve that the vacuum pump ataches to then the valve stops anything getting back in, might work for my idea, as I understand it you can make several kinds of light inside a vacuum, I have constantan a resisitance wire capable of making alot of light without a vacuum, sadly after certain current it kind of goes bang quietly, before then you can cut a slice of of a workbench in physics class though... and they're about 2inches thick and all the layers of varnish go on fire and poison you...

Speechlessly amazing!

i worked with neon tube, it's pretty easy to close a glass tube while it's in vacuum, promise! and fuse two tubes but it would be hard to calibrate the tubes to the right tolerances. and uniformity. he's a real craftsman himself. i love his analog graph plotter! it made me think that i n*ver learned anything! XD


10 years ago

Someone on hack-a-day found ythe web page to go with the video:
It's got lots of references. All in french, but still probably useful.

There was also an "Amateur Scientist" article in Scientific American, May 1964, and I recognize some of the techniques I remember reading about in there. You DO all have a copy of the Amateur Scientist CD, right? ALL the old articles from when the projects were pretty substantial (sadly, I've come to realize that many of the articles are like Instructables' Videos; a mere tastes and tease of a great project that you probably can't duplicate without a LOT of additional research. Still fun, and not ALL of the articles are like that.)


10 years ago

I don't generally like the new video instructables, but recently there have been some very well done examples. This one certainly belongs at the top of the list. Thanks for sharing this. A+

Amazing !

I was looking for a video like that about vacuum tubes for a long time, and it was on dailymotion, and you found it ! Thank you Westfw ! =o)

Someone posted a link on rcgroups, and i found it there.

WOW! thats amazing! Someone has a little too much free time!


10 years ago

That's the coolest thing I've seen in a long time. I can honestly say I never watch online videos that are longer than 2 min, but I stuck with this to the fin...

Most of his tools are DIY...the pump(s) too...Raises as many questions as it answers...

And dig that antique spot-welding rig.